The present invention relates generally to a method of mixing fluids in a well bore so that the resultant mixture may be used to effectuate a change in a downhole tool. Specifically, the method of the present invention relates to setting an inflatable packing device or packer at a location in a well bore, and an apparatus or assembly usable for performing the method.
Many downhole devices are actuated or operated in response to the application of pressurized fluid. Examples of these devices include hydraulically set packers and liner hangers, hydraulic stage cementing collars, pressure actuated perforating gun firing heads, and inflatable packers. In all of these devices, the application of pressurized fluid, to the device, effectuates a change in the device. Hydraulically set packers and liner hangers deploy slips and packing elements in response to the proper application of pressurized fluid. Stage cementing collars shift internally so as to communicate the internal diameter of well bore casing with the outer diameter of that casing. Perforating gun firing heads initiate detonation in the gun in response to the application of fluid pressure. The common element in all of these types of devices is that when pressurized fluid is communicated to the device, that communication effectuates a utilitarian change to the device. Inflatable packing devices such as packers, plugs, bridge plugs, and the like are commonly utilized in the operation or maintenance of subterranean wells. These inflatable packing devices normally comprise an inflatable elastomeric bladder concentrically disposed around a central body portion such as a tube or mandrel. Typically, a sheath of reinforcing slats or ribs is concentrically disposed around the bladder and a thick-walled elastomeric packing cover is concentrically disposed around at least a central portion of the sheath. Such inflatable packing devices may be deployed in a well bore by using tubing or a downhole electric wireline to support the device and to lower the device to a location in the well bore. Typically the inflatable packing device is connected to the electric wire line or tubing at the bottom of a downhole pump device. An assembly of these components is lowered into the well bore at a location below the extent of the production tubing.
Pressurized fluid may be pumped to the inflatable packing device from the top of the well through a pumping line. Alternatively, the inflation fluid (e.g., fresh water) may be transported to the vicinity of the inflatable packing device and then pumped into the inflatable packer. After the inflatable packing device is sufficiently inflated to seal the well bore, it is released from the electric wireline or tubing, and the electric wireline or tubing is retrieved from the well bore
Among several objects of the invention, a general object of the invention is to provide an improved downhole apparatus for inflating and/or setting an inflatable packing device or packer in a well bore. It is another general object of the invention to provide an improved method of inflating and/or setting an inflatable packer in a well bore. It is yet another general object of the invention to provide a fluid supply housing adapted for use with existing downhole equipment and/or installations.
An inflatable packer setting tool assembly, according to the invention, is lowerable into a subterranean well bore and operable to set an inflatable packer therein. The tool assembly includes an inflatable packer setting tool and a fluid supply housing. The setting tool is releasably interconnected to an inflatable packer, and includes a pump that is fluidly interconnected with the inflatable packer and operable to inflate the inflatable packer. The setting tool may be one of variety of setting tools commercially available in the industry. In one aspect of the invention, at least one fluid supply housing is provided that is adaptable or retrofittable onto such a variety of existing setting tools.
The fluid supply housing is interconnected with the setting tool and includes an inflation fluid passageway that has an inlet and an outlet that is fluidly interconnected with a suction side of the pump. The inlet is fluidly interconnected to a source of first inflation fluid present in the well bore when the setting tool assembly is lowered into the well bore. The first inflation fluid source may be surrounding well bore fluid or may be a volume of fluid (e.g., bailed fluid) lowered from the surface (e.g., fresh water lowered with the setting tool assembly). Preferably, the supply housing includes a filter housing through which the second inflation fluid must pass prior to passing through the inflation fluid passageway. More preferably, the supply housing has an outer wall which has a fluid inlet (e.g., a plurality of apertures) that fluidly communicates the inflation fluid passageway with the source of the first inflation fluid.
The supply housing also includes a reservoir(s) for containing a second inflation fluid (e.g., a water-soluble oil). Preferably, the reservoir includes a spring-loaded movable piston that allows for the volume of the second inflation fluid in the reservoir to vary (e.g., due to thermal expansion of the second inflation fluid). The reservoir has an outlet that is interconnected with the inflation fluid passageway. Thus, the setting tool (i.e., the pump) is operable to draw first and second inflation fluids from the supply housing and to deliver a mixture of the first and second inflation fluids to the inflatable packer so as to inflate inflatable packer. The fluid passageway may be configured so as to pass or deliver a predetermined concentration of one inflation fluid to a second inflation fluid (e.g., 5 to 1, or 10 to 1). This may be done by sizing certain components accordingly, employing one or more metering orifices, and/or employing a venturi device or other fluid control devices (e.g., a dedicated injection pump).
A fluid supply housing, according to the invention, is retrofittable onto an existing setting tool and/or an existing electrical wireline. In one embodiment, the supply housing includes an adapter that may be fluidly and/or electrically engageable or interconnectible with a setting tool. Further, the supply housing may include a portion of an electrical circuit that extends from an interface between the supply housing and the electrical wire line, to an interface between the supply housing and the setting tool. With this embodiment, the electrical wireline may be used to electrically interconnect or to power the setting tool.
A method of setting an inflatable packing device in a well bore, according the invention, includes first releasably connecting a setting tool with an inflatable packer (i.e., such that a pump of the setting tool is fluidly interconnected with the inflatable packer) and interconnecting a fluid supply housing with the setting tool, to form a setting tool assembly. Preferably, a reservoir of the supply housing is provided with an inflation fluid such as a water-soluble oil. Further, the setting tool assembly may be structurally and electrically interconnected with a downhole electric wire line. The electric wire line may then be used to lower the setting tool assembly into the well bore at a location wherein a second inflation fluid is present, and such that the pump of the setting tool is in fluid communication with the second inflation fluid. The pump is then operated to draw the first and second inflation fluids and to deliver a mixture of the first inflation fluid and the second inflation to the inflatable packer, thereby inflating the inflatable packer. Preferably, the method includes the step of mixing the first inflation fluid and the second inflation fluid to create a predetermined mixture, and wherein the step of operating the pump delivers a volume of the mixture to the packer to inflate the packer therewith. After operating the pump, the inflatable packer may be released from the setting tool and the setting tool and the supply housing may be raised from the well bore.
In one application, the mixture consists of at least five parts well bore fluid (e.g., brine, water, condensate, etc.) to one part water-soluble oil. Alternatively, the mixture may be composed of a first inflation fluid having a relatively high volumetric coefficient of thermal expansion but relatively good lubricity properties, and a second inflation fluid having a relatively low volumetric coefficient of thermal expansion and relatively poor lubricity. The resulting mixture is an improved inflation fluid which promotes efficiency, longer life of components, and reliability.